[ntpsec-main commit] Fix a type clash found by Coverity.

[Eric S. Raymond]

Module:    ntpsec-main
Branch:    master
Commit:    4ac004b10abc244c91cb1a67fad70d0c1f79b9af
Changeset: http://git.ntpsec.org//commit/?id=4ac004b10abc244c91cb1a67fad70d0c1f79b9af

Author:    Eric S. Raymond <esr at thyrsus.com>
Date:      Sat Nov  7 10:40:35 2015 -0500

Fix a type clash found by Coverity.

This involved reverting slightly erroneous booleanization in the calendar code.
There was no practical effect of the error except when a date calculation
overflowed, which is why it was hard to spot by eyeball.

---

 include/ntp_calendar.h |  8 ++++----
 libntp/ntp_calendar.c  | 21 +++++++++++----------
 ntpd/refclock_nmea.c   |  3 ++-
 3 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/include/ntp_calendar.h b/include/ntp_calendar.h
index 9aabef0..8f89374 100644
--- a/include/ntp_calendar.h
+++ b/include/ntp_calendar.h
@@ -222,7 +222,7 @@ ntpcal_date_to_rd(const struct calendar * /* jt */);
  * for regular years and a non-zero value for leap years.
  */
 extern ntpcal_split
-ntpcal_split_eradays(int32_t /* days */, bool * /* isleapyear */);
+ntpcal_split_eradays(int32_t /* days */, int32_t * /* isleapyear */);
 
 /*
  * Given a number of elapsed days in a year and a leap year indicator,
@@ -235,10 +235,10 @@ ntpcal_split_yeardays(int32_t /* eyd */, bool /* isleapyear */);
 
 /*
  * Convert a RataDie number into the date part of a 'struct
- * calendar'. Return false if the year is regular year, true if the year is
- * a leap year.
+ * calendar'. Return 0 if the year is regular year, 1 if the year is
+ * a leap year, -1 if the calculation overflowed.
  */
-extern bool
+extern int
 ntpcal_rd_to_date(struct calendar * /* jt */, int32_t /* rd */);
 
 /*
diff --git a/libntp/ntp_calendar.c b/libntp/ntp_calendar.c
index d1e2c04..bf63e44 100644
--- a/libntp/ntp_calendar.c
+++ b/libntp/ntp_calendar.c
@@ -511,7 +511,7 @@ priv_timesplit(
 ntpcal_split
 ntpcal_split_eradays(
 	int32_t days,
-	bool  *isleapyear
+	int32_t *isleapyear
 	)
 {
 	ntpcal_split res;
@@ -594,20 +594,21 @@ ntpcal_split_yeardays(
 /*
  *---------------------------------------------------------------------
  * Convert a RD into the date part of a 'struct calendar'.
+ * Returns -1 on calculation overflow.
  *---------------------------------------------------------------------
  */
-bool
+int
 ntpcal_rd_to_date(
 	struct calendar *jd,
 	int32_t		 rd
 	)
 {
 	ntpcal_split split;
-	bool	     leaps;
-	bool	     retv;
+	int32_t	     leaps;
+	int32_t	     retv;
 
-	leaps = false;
-	retv = false;
+	leaps = 0;
+	retv = 0;
 	/* Get day-of-week first. Since rd is signed, the remainder can
 	 * be in the range [-6..+6], but the assignment to an unsigned
 	 * variable maps the negative values to positive values >=7.
@@ -620,7 +621,7 @@ ntpcal_rd_to_date(
 		jd->weekday += 7;
 
 	split = ntpcal_split_eradays(rd - 1, &leaps);
-	retv  = leaps;
+	retv  = (int)leaps;
 	/* get year and day-of-year */
 	jd->year = (uint16_t)split.hi + 1;
 	if (jd->year != split.hi + 1) {
@@ -649,7 +650,7 @@ ntpcal_rd_to_tm(
 	)
 {
 	ntpcal_split split;
-	bool	     leaps;
+	int32_t	     leaps;
 
 	leaps = 0;
 	/* get day-of-week first */
@@ -667,7 +668,7 @@ ntpcal_rd_to_tm(
 	utm->tm_mon  = split.hi;	/* 0-based */
 	utm->tm_mday = split.lo + 1;	/* 1-based */
 
-	return leaps;
+	return leaps != 0;
 }
 
 /*
@@ -1055,7 +1056,7 @@ ntpcal_rd_to_mstart(
 	)
 {
 	ntpcal_split split;
-	bool	     leaps;
+	int32_t	     leaps;
 
 	split = ntpcal_split_eradays(rd - 1, &leaps);
 	split = ntpcal_split_yeardays(split.lo, leaps);
diff --git a/ntpd/refclock_nmea.c b/ntpd/refclock_nmea.c
index b3f954a..64e9ff3 100644
--- a/ntpd/refclock_nmea.c
+++ b/ntpd/refclock_nmea.c
@@ -1631,7 +1631,7 @@ parse_weekdata(
  * The function updates the calendar structure it also uses as
  * input to fetch the time from.
  *
- * returns 1 on success, 0 on failure
+ * returns true on success, false on failure
  * -------------------------------------------------------------------
  */
 static bool
@@ -1656,6 +1656,7 @@ unfold_day(
 					   ntpcal_date_to_daysec(jd),
 					   SECSPERDAY);
 	rec_ds.hi += ntpcal_daysec_to_date(jd, rec_ds.lo);
+	/* -1 return means calculation overflowed */
 	return (ntpcal_rd_to_date(jd, rec_ds.hi + DAY_NTP_STARTS) >= 0);
 }